A workaround for JuliaLang/julia#13359 in Julia 0.6 and (to a lesser extent) 0.7, avoiding the penalty of splatting arguments by passing the underlying argument collection and its length to a generator function that builds a call expression with indexed arguments.

For example:

julia> @noinline foo(a,b,c) = a+b+c
julia> bar(args) = foo(args...)
julia> @code_llvm bar(SVector(1,2,3))
...
  call nonnull %jl_value_t addrspace(10)* @jl_f__apply(...)
...

julia> using FastSplat
julia> bar(args) = @fastsplat foo(args...)
julia> @code_llvm bar(SVector(1,2,3))
...
  call i64 @julia_foo(i64, i64, i64)
...

Note that this will only generate better code when the length of an array is known to the type system, eg. when the argument is a Vararg, Tuple or SVector.